Currently, clamshell electronic devices such as notebook computer, flip mobile phone usually have only one folded state (e.g., a folded state and an unfolded state). Thus, in the folded state, a main display screen of the electronic devices is covered, whereas in the unfolded state, the main display screen thereof is not covered. This simple switching between the folded state and the unfolded state usually can only implement a switching between an operating state and a standby state.